The current password based unlocking methods requires inconvenient manual password input every time, which is vulnerable because strangers can steal your pattern or passcode while you draw the pattern or type in passcode. An automatic unlocking method to resolve this problem could greatly improve user experience.
Additionally, Prevalence of wearable devices is increasing. Wearable devices include many features like proximity sensor, heart rate sensor, accelerometer, gyroscope, BLUETOOTH connectivity and so on. Using proximity sensor to automatically unlock a device is not secure enough since the device could be stolen and still be used near the user. It requires more complex combination of sensors to effectively unlock a device with security in mind in addition to convenience.